JPH06157230A - Production of inorganic filler and dental filling/ repairing material - Google Patents

Abstract

PURPOSE:To obtain an inorganic filler for dental filling/repairing materials of high mechanical strength and having gloss comparable to that of human teeth by mixing silica-based metallic oxides having at least two kinds of mean particle diameter followed by baking at a specified temperature. CONSTITUTION:Unbaked silica-based multiple oxides having at least two kinds of mean diameter with the mean particle diameter ratio of 4 to 20 are mixed and the resulting mixture is baked at a temperature below the sintering temperature (pref. 700-1100 deg.C) to obtain the objective filler. For this filler, respective particles are homogeneously dispersed and mixed; therefore, being fillable in high density. Furthermore, this filler can be used for dental filling/repairing materials not only excellent in surface smoothness and gloss but also having excellent physical properties. It is preferable that the range of the mean particle diameter for the filler fall between 0.01 and 100mum. The mixing operation can be made using a dispersion medium such as methanol, acetonitrile or water, with e.g. a ball mill, vibratory ball mill, attrition mill, grinder, hybridizer with high-speed jet stream method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a silica-based inorganic filler and a dental filling material which is filled with the filler and has high strength and high aesthetics.

[0002]

2. Description of the Related Art Dental filling / restoring materials which are widely used for restoration of tooth defects or entire crowns due to dental caries, fractures, etc. and fixation of moving teeth are generally composed of polymerizable monomers and inorganic fillers. It The properties required for such a dental filling / restoring material are mechanical strength capable of withstanding high occlusal pressure during chewing, thermal expansion coefficient comparable to that of tooth substance, and low polymerization shrinkage for preventing separation from tooth substance during polymerization hardening. The physical properties such as the ratio, the color tone similar to that of natural teeth and the smoothness upon contact with the tongue in order to enable restoration with a natural feel, and the like are mentioned.

[0003] Conventionally, as a filler for such a restoration material, a glass containing quartz or silica as a main component is mechanically pulverized to have a particle size of several μm to 150 μm, or a thermal decomposition method or precipitation of an aqueous solution is used. Silica having a primary particle size of less than 0.05 μm synthesized by a precipitation method or a gas phase reaction method has been used. However, the former is capable of increasing the compressive strength and the coefficient of thermal expansion because it can be filled with about 80 wt% of the filler, but the large particle size of the filler causes the surface smoothness and glossiness after finish polishing to be inferior. Although it is excellent in properties, the filling rate becomes low at most about 60 wt% due to the increase in the specific surface area of the filler, which causes problems such as low physical and engineering properties.

Therefore, it has been attempted to make the particles finer and to fill them with higher density in order to achieve both physical and engineering properties and aesthetic properties. For example, in the technique disclosed in JP-A-57-82303, the particle size range is 0.1 to 100 μm and the average particle size is 0.1.
2 to 20 μm inorganic powder and particle size range 10 to 100 μm,
It has been sought to improve the mechanical strength by combining inorganic powders having an average particle diameter of 10 to 50 μm, that is, by combining several kinds of fillers having different particle diameters to make the filler finely packed. In addition, JP-A-61
-134307 discloses a combination of 0.05 μm fumed silica and silica with an average particle size of 5 μm.

Recently, further miniaturization of the filler has been studied, and Japanese Patent Laid-Open No. 3-258707 discloses spherical silica synthesized from silicon alkoxide and having an average particle size of 0.01 to 5 μm.

However, the filler having such a particle size can have a filling rate of 80 wt% or more.
Since the particle size is large, surface lubricity is not satisfactory.

According to the results of studies by the present inventors, the particle size of the filler must be 1 μm or less in order to obtain the same gloss as natural teeth. On the other hand, the filling rate is preferably higher than 80 wt% in order to satisfy the physical and engineering properties.

Therefore, a filler having a particle diameter of 1 μm or less and having a filling rate of more than 80 wt% when filled in a resin is desired, but particles having a particle diameter of 1 μm or less cannot be obtained by the mechanical pulverization method. It is difficult and requires operations such as classification,
In addition, since it is difficult to control the particle size distribution at a high level, 80 wt
It is not possible to obtain a filling factor exceeding%.

As a method for highly controlling the particle size in the submicron to micron range, a method has been reported in which metal oxide particles are used as a starting material to precipitate metal oxide particles from a solution (Japanese Patent Publication No. 2797
6, Japanese Patent Publication No. 1-38044, Japanese Patent Publication No. 38043).

Japanese Unexamined Patent Publication (Kokai) No. 3-258707 discloses a dental filling / restoring material in which silica particles having particle sizes of submicron and several microns are synthesized by a hydrolysis method of tetraethyl silicate, and the mixture is used as a filling material. There is.
However, the mixing method is such that 1
After firing at a temperature of 000 ° C. or higher, mixing is performed using a ball mill. However, according to this method, silica particles calcined at a high temperature such as 1000 ° C. are likely to form tightly bound agglomerates, and especially with a particle size of about 0.1 μm, the agglomerates generated during calcining are treated like a ball mill. It cannot be disintegrated into a monodisperse state by a mechanical method. Therefore, the filling rate is lowered, and the physical properties of science and engineering are lowered. In addition, such a method requires a long time of 80 hours for mixing, and there is a problem that impurities may be mixed from the container and the crushing balls when mechanically mixing for a long time.

As described above, an inorganic filler satisfying the filling rate of 81 wt% or more and the surface lubricity has not yet been obtained.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to develop a dental filling / restoring material which is filled with an inorganic filler in an amount of 81% or more and has a high strength and a gloss equivalent to that of a human tooth.

[0013]

DISCLOSURE OF THE INVENTION As a result of intensive studies in view of solving the above problems, the present invention has at least two different average particle sizes, and the ratio of the average particle sizes of both is in the range of 4 to 20 times. The mixed particles prepared by mixing the unsintered silica-based composite oxide, which is a material, and then calcining at a temperature lower than the sintering, each particle is uniformly dispersed and mixed, and when used as a filler, it is densely packed. It was found that it was possible, and the average particle diameter produced by the above-mentioned production method was 0.1 μm.
Less than 10 to 50% by weight of silica-based inorganic oxide and a particle size of 0.
The filler in which 50 to 90% by weight of the silica-based inorganic oxide of 5 to 1 μm is mixed has particles of 0.1 μm or less uniformly dispersed, and thus it has been difficult so far when the polymerizable monomer is filled. A high filling rate of 81 wt% or more was obtained, and not only excellent surface lubricity and gloss but also excellent filling / restoring material for dentistry was developed.

The unsintered silica-based composite oxide used in the present invention is not particularly limited, but is generally silica synthesized by a hydrolysis method of metal alkoxide, or a composite oxide containing silica as a main component with another metal. The shape is a spherical or irregular shape close to a sphere.

Specific examples of the unsintered silica-based composite oxide include silica, silica-titania, silica-zirconia, silica-barium oxide, silica-alumina,
Silica-calcia, silica-strontium oxide, silica-magnesia, silica-titania-sodium oxide, silica-titania-potassium oxide, silica-zirconia-sodium oxide, silica-zirconia-potassium oxide, silica-alumina-sodium oxide, or silica. -Alumina-
Examples thereof include potassium oxide.

When the unsintered silica-based composite oxide is used as an inorganic filler, one having at least two kinds of average particle diameters is combined for the purpose of increasing the filling rate. The ratio of the average particle size may be in the range of 4 to 20, but more preferably in the range of 5 to 15. Specifically,
Less than 0.1 μm, 0.5-1 μm, 0.01 μm-0.
Those satisfying the above-mentioned average particle size ratio are preferably selected from combinations in the range of 1 μm and 0.1 μm to 2 μm, 0.1 to 0.5 μm and 0.5 μm to 10 μm, or 0.5 μm to 10 μm and 10 μm to 100 μm. Be done.

As a method for mixing the above-mentioned at least two types of uncalcined silica-based composite oxides, any known method can be used without any limitation. However, monodispersity is obtained by crushing aggregates of particles having a particle size of 0.1 μm or less. For the purpose of increasing the temperature, a ball mill by mechanical pressure, a ball medium mill such as a vibrating ball mill, an attritor, or a kneading machine such as a liquor machine used for kneading a pasty material is preferably used. Furthermore, it is possible to use a hybridizer, which has been attracting attention as a mechanochemical surface modification method for powders in recent years, such as a high-speed air impact method such as the Nara Kikai Seisakusho Hybridizer or the Hosokawa Micron Hybridizer. The impact crushing method is preferably used.

It is also preferable to use an appropriate dispersion medium at the time of mixing in order to increase the crushing dispersion efficiency. The dispersion medium is not particularly limited, but it is polar because of its wettability with the surface of the unburned silica-based composite oxide. Solvents are preferable, and alcohols such as methanol, ethanol and isopropanol, 1,2-
Propanediol, diols such as 1,4-butanediol, glycols such as ethylene glycol, propylene glycol and diethylene glycol, glycerin, formamide, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, acetonitrile, water and the like are preferably used. Two or more kinds of solvents may be used in combination, and addition of a small amount of a surfactant to these dispersion media is also suitably adopted as a method for improving dispersibility.

In order to impart sufficient surface gloss to the dental filling and restorative material, the particle diameter of the inorganic filler may be 1 μm or less, but the average particle diameter is less than 0.1 μm and the average particle diameter is less than 0.1 μm. A powder having at least two different particle size distributions selected from powders having a diameter in the range of 0.5 to 1 μm is preferable. Furthermore, in order to obtain a high filling efficiency, the ratio of the average particle diameters of the two is combined in the range of 4 to 20, but particularly 5 to 1.
The range of 5 is more preferable. If the particle size ratio is smaller than 4 or larger than 20, the packing efficiency is greatly reduced. Further, the blending ratio of both is in the range of 10 to 50% by weight and 50 to 90% by weight of the powder having the average particle diameter of less than 0.1 μm and the powder having the average particle diameter of 0.5 to 1 μm, respectively. Is preferable in order to obtain a high filling rate, and a higher filling rate can be obtained if it is in the range of 20 to 40% by weight to 80 to 60% by weight.

The inorganic filler of the present invention is obtained by firing a pre-mixed unsintered silica-based composite oxide having a plurality of average particle diameters at a specific temperature for the purpose of improving strength and chemical stability. can get. Even if the unburned silica-based composite oxides having different particle diameters are previously fired individually and then mixed to form an inorganic filler, the inorganic filler is mixed with a polymerizable monomer described below to form a dental filling restoration material. In this case, a high filling rate of 81 wt% or more cannot be achieved.

The firing temperature varies depending on the composition and particle size of the silica-based composite oxide, but it is essential that the firing is performed at a temperature below the temperature at which the silica-based composite oxide is sintered.
Specifically, within 200 ° C below the sintering temperature, preferably 1
It is desirable that the temperature is within the range of 00 ° C from the viewpoint of strength and chemical stability. When the firing temperature is as low as more than 200 ° C. from the sintering temperature, the particle surface may be in a porous state, and sufficient strength and chemical stability cannot be obtained. Further, if it is fired at a sintering temperature or higher, it cannot be crushed into a monodisperse state after firing. A concrete example of the firing temperature is a particle size of 1 μm.
Since the spherical silica particles of No. 1 start to sinter at 1050 ° C., the calcination temperature is preferably in the range of 800 to 1000 ° C., more preferably 900 ° C. The mooring time may be about 30 minutes to 2 hours, but it is preferable to calcine for 1 hour.

The dental filling / restoring material of the present invention is obtained by mixing the inorganic filler obtained by the above-mentioned production method and the weight monomer containing the polymerization initiator. The mixing ratio of the inorganic filler and the polymerizable monomer is 81 to 90 parts by weight of the inorganic filler and 10 to 19 parts by weight of the polymerizable monomer (however, the total amount of the inorganic filler and the polymerizable monomer is 100 parts by weight). If it is selected from the range (part), a dental filling and restorative material having excellent mechanical strength and a coefficient of thermal expansion close to that of the tooth substance can be obtained. Furthermore, the inorganic filler is 83-
The range of 88 parts by weight is more preferable in terms of achieving both mechanical strength and easy operability in filling the cavity of the tooth and imparting form. If the amount of the inorganic filler is less than 81 parts by weight, the mechanical strength is significantly lowered, and if it is more than 90 parts by weight, the property as a paste is lost and the operability is deteriorated.

When an inorganic filler is used as a filler for a dental filling / restoring material, it is generally treated with a surface treating agent represented by a silane coupling agent for the purpose of improving strength and durability. The surface treatment method may be performed by a known method, and the silane coupling agent may be γ-methacryloxypropyltrimethoxysilane, ε-methacryloxyoctyltrimethoxysilane, κ-methacryloxydecyltrimethoxysilane, vinyltrimethoxysilane. Etc. are preferably used.

Further, the polymerizable monomer to be combined with the inorganic filler is not particularly limited, and a monomer having a methacrylic group acrylic group generally used for dentistry is widely used. Specifically exemplifying the above-mentioned monomer having an acrylic group and / or a methacrylic group,
Bisphenol A diglycidyl (meth) acrylate (methacrylate compound is hereinafter referred to as bis-GMA), triethylene glycol di (meth) acrylate (methacrylate compound is hereinafter referred to as 3G), pentaerythritol tri (meth) acrylate, having the following structure

[0025]

[Chemical 1]

(In the above formula, R1, R2, R3 and R4 are the same or different H or CH3, and A is

[0027]

[Chemical 2]

A urethane-based tetrafunctional compound or the like (which represents any of the groups) is used.

Further, a plurality of these polymerizable monomers may be appropriately combined for the purpose of adjusting the viscosity and the refractive index.

Any known initiator may be used without limitation as the initiator used for initiating the polymerization, but a radical is generated by heating, or a radical is generated by a reaction between a peroxide and a tertiary amine at room temperature. In addition, those that generate radicals by exposure to light such as visible light and ultraviolet rays are appropriately selected according to the application.

Illustrative examples of each of the typical compounds are 2,2-
Azo compounds such as azobisisobutyronitrile, 4,4′-azobis (cyanovaleric acid), benzoyl peroxide, and the like are preferable, and as the initiator that generates a radical by light rays, camphorquinone, α-naphthyl, Α such as benzyl
Among the suitable use of diketone, it is preferable to use camphorquinone. Further, these photoinitiators include N, N-dimethyl-P-toluidine, N, N-diethanol-P-toluidine, dimethylaminobenzoic acid and its ethyl ester, and N, N-dimethylaminoethylmethacrylate as reducing agents. Tertiary amines are combined. The addition amount of these polymerization initiators may be appropriately determined,
It is used in an amount of 0.1 to 10, preferably 0.3 to 3 parts by weight, based on 100 parts by weight of the polymerizable monomer.

In addition to the above essential components, an ultraviolet absorber,
A radical polymerization inhibitor, a pigment for adjusting the color tone, etc. are appropriately added as an additive.

The method of mixing the inorganic filler, the polymerizable monomer, the polymerization initiator, and the additives used as necessary is not particularly limited, and a known method is adopted. Usually, to a specific amount of inorganic filler placed in the mixer, gradually add a polymerizable monomer containing a polymerization initiator and any additive,
Mix and add until no paste appears.

[0034]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Various physical properties in the present invention were measured as follows.

[Measurement of Diameter] A laser scattering type particle size distribution measuring device (FOTAL3300, manufactured by Otsuka Electronics Co., Ltd.) was used for measurement.

[Mechanical Strength] <Compressive Strength> A stainless steel mold having a hole of 4 mmΦ × 3 mm was filled with the paste and pressed with a polypropylene sheet, and then the sheet was irradiated with white light from a light source manufactured by Takara Belmont Co., Ltd. from above the sheet. Irradiate for 30 seconds. The cured product was taken out of the mold, further heated at 100 ° C. for 20 minutes, immersed in 37 ° C. water for 24 hours, and then measured at a crosshead speed of 10 mm / min using a Shimadzu tester autograph.

<Tensile Strength> A stainless steel mold having holes of 6 mmΦ × 4 mm was filled with the paste, pressed with a polypropylene sheet, and then irradiated with a white light from a light source manufactured by Takara Belmont Co., Ltd. for 30 seconds from above the sheet. Remove the cured product from the mold and add 100 more
The one heated at 20 ° C. for 20 minutes was immersed in 37 ° C. water for 24 hours, and then measured at a crosshead speed of 10 mm / min using a Shimadzu tester autograph.

<Bending Strength> A stainless steel split mold having holes of 25 mm × 2 × 2 was filled with the paste and pressed with a polypropylene sheet, and then the sheet was made on a polypropylene sheet by a white light illuminator manufactured by Takara Belmont Co. Was irradiated with light for 30 seconds on each of the three surfaces. The cured product was taken out from the split mold and further heated at 100 ° C. for 20 minutes and immersed in 37 ° C. water for 24 hours, and then a crosshead speed of 0.5 was obtained using a Shimadzu tester autograph.
It was measured at mm / min.

[Surface smoothness] 20 mm × 10 mm × 4 m
The paste was filled in a Teflon mold of m and light-irradiated for 3 minutes using a technical irradiation device Alpha Light to prepare a cured product. Next, the surface of the hardened body is poured under water, # 800, # 10.
After buffing with 00 and # 1500 emery paper, buffing was further performed. The surface roughness Ra value of the polished surface was measured by Surfcom manufactured by Tokyo Seimitsu Co., Ltd.

[Surface Glossiness] A test piece prepared by the above-described method of measuring surface roughness was used as a gloss meter (model TC-
108D) at a reflection angle of 45 °.

Production Example 1 Synthesis of spherical silica particles having an average particle size of 0.7 μm Tetraethyl silicate while stirring in an ammoniacal alcohol solution in which 400 g of methyl alcohol and 100 g of 25% ammonia water were introduced into a glass container with an internal volume of 3 l equipped with a stirrer. , Nippon Colcoat Chemical Co., Ltd., trade name "Ethyl silicate 28" was added and stirred for 30 minutes, and then 2000 g of tetraethyl silicate and 640 g of 25% aqueous ammonia were simultaneously added dropwise over 4 hours. The temperature of the reaction solution during the reaction was kept at 35 ° C. After completion of the reaction, the mixture was stirred for additional 30 minutes, the solvent was distilled off, and the residue was air-dried at 100 ° C to obtain a white powder (A-1). The obtained powder is
Particle size range 0.68 to 0.76 μm, average particle size 0.72 μ
m, and its shape was a true sphere as observed by a scanning electron microscope (hereinafter referred to as SEM).

Production Example 2 Synthesis of spherical silica particles having an average particle size of 1 μm Tetraethyl silicate, Japan, while stirring in an ammoniacal alcohol solution in which 375 g of methyl alcohol and 125 g of 25% ammonia water were introduced into a glass container with an internal volume of 3 l equipped with a stirrer. 10 g of "Ethyl silicate 28" manufactured by Colcoat Chemical Co., Ltd. was added and stirred for 30 minutes, and then 2000 g of tetraethyl silicate and 640 g of 25% aqueous ammonia were simultaneously added dropwise over 4 hours. The temperature of the reaction solution during the reaction was kept at 40 ° C. After completion of the reaction, the mixture was stirred for additional 30 minutes, the solvent was distilled off, and the residue was air-dried at 100 ° C to obtain a white powder (A-2). The obtained powder is
Particle size range 0.96 to 1.06 μm, average particle size 1.02 μ
m, and the shape was a true sphere from SEM observation.

Production Example 3 Synthesis of spherical silica particles having an average particle size of 2 μm Tetraethyl silicate, Japan, while stirring in an ammoniacal alcohol solution in which 400 g of ethyl alcohol and 100 g of 25% ammonia water were introduced into a glass container with an internal volume of 3 l equipped with a stirrer. 10 g of "Ethyl silicate 28" manufactured by Colcoat Chemical Co., Ltd. was added and stirred for 30 minutes, and then 2000 g of tetraethyl silicate and 640 g of 25% aqueous ammonia were simultaneously added dropwise over 4 hours. The temperature of the reaction solution during the reaction was kept at 40 ° C. After completion of the reaction, the mixture was stirred for another 30 minutes, the solvent was evaporated, and the residue was air-dried at 100 ° C to obtain a white powder (A-3). The obtained powder is
Particle size range 1.89 to 1.96 μm, average particle size 1.94 μm
m, and the shape was a true sphere from SEM observation.

Production Example 4 Silica with an average particle size of 0.08 μm
Synthesis of titania particles Tetraethyl silicate, manufactured by Nippon Corcoat Chemical Co., Ltd., 176.6 g of trade name "Ethyl silicate 28" is mixed with 400 g of methanol, and 5 g of 0.04% hydrochloric acid aqueous solution is added thereto, and water is added while stirring at a temperature of 30 ° C for about 1 hour. Disassembled. Then, 21.4 g of tetrabutyl titanate (manufactured by Nippon Soda Co., Ltd.), sodium methyler and a methanol solution (concentration 28% by weight) were added to this solution in 210 g of isopropyl alcohol.
The solution dissolved in was mixed with stirring to prepare a mixed solution of tetraethyl silicate and tetrabutyl titanate. Next, 1050 g of methanol was introduced into a glass container having an internal volume of 3 l equipped with a stirrer, and 250 g of 25% by weight ammonia aqueous solution was added thereto to prepare an ammoniacal alcohol solution. A solution prepared by dissolving 0.8 g of tetraethyl silicate for producing silica seed particles in 15 g of methanol was added thereto, and when the reaction solution became milky after the addition was completed, the above mixture was further added dropwise over about 5 hours. During the reaction, the temperature of the reaction caustic was kept at 40 ° C. After the dropping was completed, the mixture was stirred for another 30 minutes, and then the solvent was distilled off to collect milky white particles. The recovered particles were further dried at 100 ° C. to obtain silica-titania white powder (B-1). The obtained powder has a particle size range of 0.080 to 0.095 μm,
The average particle diameter was 0.084 μm, and the shape was spherical from SEM observation.

Production Example 5 Synthesis of silica-titania spherical particles having an average particle size of 0.2 μm 176.6 g of tetraethyl silicate, trade name “Ethyl silicate 28” manufactured by Nippon Corcoat Chemical Co., Ltd. was mixed with 400 g of methanol, and 0.04% hydrochloric acid was added. 5 g of an aqueous solution was added, and hydrolysis was performed while stirring at a temperature of 30 ° C. for about 1 hour. Thereafter, 37.7 g of tetrabutyl titanate (manufactured by Nippon Soda Co., Ltd.), sodium methylate and a methanol solution (concentration 28% by weight) were added to this solution in isopropyl alcohol 210.
The solution dissolved in g was mixed with stirring to prepare a mixed solution of tetraethyl silicate and tetrabutyl titanate. Next, in a glass container with a stirrer and an internal volume of 3 l, 400 g of methanol and 700 g of isobutyl alcohol were added.
g, and 25% by weight aqueous ammonia solution 250
g was added to prepare an ammoniacal alcohol solution. To this, a solution of 1.8 g of tetraethyl silicate for making silica seed particles in 15 g of methanol was added, and when the reaction solution became milky after the addition was completed,
Further, the above mixture was added dropwise over about 5 hours. During the reaction, the temperature of the reaction caustic was kept at 40 ° C. 3 more after dropping
After stirring for 0 minutes, the solvent was distilled off to collect milky white particles. The collected particles are further dried at 100 ° C. to obtain silica-
A titania-based white powder (B-2) was obtained. The obtained powder has a particle size range of 0.17 to 0.22 μm and an average particle size of 0.1.
It was 9 μm, and its shape was spherical from SEM observation.

Example 1 4 g of ethylene glycol was added to 70 g of silica particles having an average particle size of 0.7 μm, and the mixture was kneaded for 30 minutes using a Likai machine. Next, average particle size 0.08 μm silica-titania particles 3
Add 0 g and knead for another 7 hours at a temperature of 900
What was calcined at 1 ° C. for 1 hour and crushed by a ball mill for 30 minutes was treated with 1.5% by weight of γ-methacryloxypropyltrimethoxysilane.

A polymerizable monomer BisGMA / 3G (in which a polymerization initiator and camphorquinone as a reducing agent and ethyl steayl dimethylaminobenzoate were dissolved in a weight ratio of 0.5% in advance in a mortar was added to the obtained surface-treated product. Weight ratio 60/40)
Was gradually added and mixed to the limit showing the paste state.
The content% by weight of the inorganic filler at this time is defined as the inorganic filling rate.

Example 2 3 g of ethylene glycol was added to 80 g of spherical unfired silica having an average particle size of 0.7 μm, and the mixture was mixed for 30 minutes by using a Likai machine. Next, 20 g of silica-titania particles having an average particle size of 0.08 μm was added, and the mixture was further mixed for 7 hours, baked at a temperature of 900 ° C. for 1 hour, and crushed with a ball mill for 30 minutes to obtain γ-methacryloxypropyltrimethoxy. The silane was treated at 1.2% by weight. Then, the mixture was mixed with the polymerizable monomer in the same manner as in Example 1 to obtain a paste.

Example 3 Mixing and firing were carried out in the same manner as in Example 2 except that 1.0 μm spherical unfired silica particles were used instead of 0.7 μm spherical unfired silica particles.

Further, the calcined product was treated with 1% by weight of γ-methacryloxypropyltrimethoxysilane, and the product was filled with a polymerizable monomer in the same manner as in Example 1 to obtain a paste-like product.

Comparative Example 1 The same procedure as in Example 1 was carried out except that 2.0 μm spherical unfired silica was used instead of 0.7 μm spherical unfired silica.

Comparative Example 2 The same procedure as in Example 1 was repeated except that 0.2 μm spherical unsintered silica-titania was used instead of 0.08 μm spherical unsintered silica-titania.

Comparative Example 3 Spherical unburned silica having an average particle size of 0.7 μm and a particle size of 0.08
The spherical unfired silica-titania having a particle size of
What was baked at 0 ° C. for 1 hour was mixed and surface-treated in the same manner as in Example 1 below, and then filled with a polymerizable monomer to obtain a paste-like material.

Comparative Example 4 The same procedure as in Comparative Example 3 was repeated except that silica particles having a particle size of 1.0 μm were used instead of the silica particles having a particle size of 0.7 μm.

Comparative Example 5 0.7 μm spherical unburned silica and 0.0
30 μg of 8 μm spherical unfired silica-titania,
It carried out similarly except having changed to 70 g.

Comparative Example 6 In Example 1, the firing conditions were changed to 1100 ° C. for 1 hour. As a result, the inorganic filler was sintered and could not be crushed.

The maximum inorganic filling rate, the surface smoothness, the surface glossiness, and the mechanical strength of the dental filling and restorative materials obtained in Examples 1 to 3 and Comparative Examples 1 to 5 were measured and shown in Table 1. Show.

[0058]

[Table 1]

[0059]

INDUSTRIAL APPLICABILITY The inorganic filler composed of a silica-based metal oxide having at least two kinds of average particle diameters obtained by the production method of the present invention has two or more kinds of particle diameters when mixed with a polymerizable monomer. Different particles can be uniformly mixed in a monodisperse state, and in particular, dispersion and mixing of particles in the submicron region is facilitated. As a result, 10 to 50% by weight of silica-based spherical inorganic oxide having a particle size of 0.1 μm or less, 0.5 μm to 1 μm
The dental filling / restoring material in which the filler obtained by mixing the silica-based spherical inorganic oxide of m in the range of 50 to 90% by weight and the polymerizable monomer are mixed has an inorganic filling rate of 81% or more. It has high strength and has the same surface gloss and surface smoothness as human teeth.

Claims (20)

[Claims] 1. At least two kinds of uncalcined silica-based composite oxides having different average particle diameters and having a ratio of the average particle diameters of both are in the range of 4 to 20 times, and then mixed at a temperature lower than the sintering temperature. A method for producing an inorganic filler, which comprises firing at a temperature. 2. The uncalcined silica-based composite oxide is silica,
Or a complex oxide of at least one metal selected from the group consisting of Group 1, Group 2, Group 3 and Group 4 of the periodic table and silica, Method for manufacturing inorganic filler. 3. The unfired silica-based composite oxide is silica,
Silica-titania silica-zirconia, silica-barium oxide, silica-alumina, silica-calcia,
Silica-strontium oxide, silica-magnesia, silica-titania-sodium oxide, silica-titania-potassium oxide, silica-zirconia-sodium oxide, silica-zirconia-potassium oxide, silica-alumina-sodium oxide, or silica-alumina-potassium. It is an oxide, The manufacturing method of the inorganic filler of Claim 1 characterized by the above-mentioned. 4. Different average particle sizes are from 0.01 μm to 100.
The method for producing an inorganic filling material according to claim 1, wherein the inorganic filling material is in the range of μm. 5. The average particle size of the two types of unsintered silica-based composite oxides is less than 0.1 μm and 0.5 to 1 μm, 0.0.
1 μm to 0.1 μm and 0.1 μm to 2 μm, 0.1
0.5 μm and 0.5 μm to 10 μm, or 0.5 μm
The method for producing an inorganic filling material according to any one of claims 1 to 3, characterized in that it is combined in the range of 10 m to 10 m and 10 m to 100 m. 6. The method for producing an inorganic filling material according to claim 1, wherein the mixture is carried out by a ball mill, a vibrating ball mill, an attritor, a liquor machine, a high-speed air flow method hybridizer, or an impact pulverization method hybridizer. 7. The method for producing an inorganic filling material according to claim 1, wherein the dispersion medium is mixed. 8. The dispersion medium is methanol, ethanol, isopropanol, 1,2-propanediol, 1,4-butanediol, ethylene glycol, propylene glycol, diethylene glycol, glycerin, formamide, dimethylformamide, dimethylsulfoxide, acetonitrile, water. The method for producing an inorganic filling material according to claim 7, wherein the method is provided. 9. The method for producing an inorganic filling material according to claim 1, wherein the firing temperature is in the range of 700 to 1100 ° C. 10. A method for producing a dental filling / restoring material, which comprises mixing the inorganic filler obtained by the method according to any one of claims 1 to 9, a polymerizable monomer, and a polymerization initiator. 11. The method for producing a dental filling / restoring material according to claim 10, wherein the inorganic filler is an inorganic filler surface-treated with a silane coupling agent. 12. The inorganic filler is 60 to 90 parts by weight, the polymerizable monomer is 10 to 40 parts by weight, and the polymerization initiator is 0.1 to 10 parts by weight per 100 parts by weight of the polymerizable monomer (however, The total amount of the inorganic filler and the polymerizable monomer is 100 parts by weight), The method for producing a dental filling / restoring material according to claim 10 or 11, wherein 13. The inorganic filler is silica, silica-titania, silica-zirconia, silica-barium oxide, silica-alumina, silica-calcia silica-strontium oxide, silica-magnesia, silica-.
Sodium oxide, silica-potassium oxide,
Silica-titania-sodium oxide, silica-titania-potassium oxide, silica-zirconia-sodium oxide, silica-zirconia-potassium oxide, silica-alumina-sodium oxide,
Or it is silica-alumina-potassium oxide, The manufacturing method of the dental filling restoration material of Claim 10-12 characterized by the above-mentioned. 14. The dental filling and restorative material according to claim 10, wherein the polymerizable monomer is a polymerizable monomer having 2 to 6 meth (acrylic) groups in its molecular structure. Manufacturing method 15. A meth (acrylic) group is incorporated into a molecular structure of 2
The polymerizable monomer having 6 to 6 is at least one polymerizable monomer selected from the group consisting of bisphenol A diglycidyl (meth) acrylate, triethylene glycol di (meth) acrylate and pentaerythritol tri (meth) acrylate. The method for producing a dental filling / restoring material according to claim 14, wherein 16. A spherical silica-based composite oxide having an average particle size of less than 0.1 μm, 10 to 50% by weight, and an average particle size of 0.5 to 1 μm.
81 to 90 parts by weight of an inorganic filler composed of 50 to 90% by weight of spherical silica-based composite oxide of m, and a polymerizable monomer 10 to 1
9 parts by weight, and 0.
A dental filling and restorative material comprising 1 to 10 parts by weight of a polymerization initiator (however, the total amount of the inorganic filler and the polymerizable monomer is 100 parts by weight). 17. The dental filling and restorative material according to claim 16, wherein the spherical silica-based composite oxide is a spherical silica-based composite oxide surface-treated with a silane coupling agent. 18. The spherical silica-based composite oxide is silica,
Silica-titania Silica-zirconia, silica-barium oxide, silica-alumina, silica-strontium oxide, silica-magnesia, silica-sodium oxide, silica-potassium oxide, silica-calcia, silica-titania-sodium oxide, silica-titania- Potassium oxide, silica-
The dental filling / restoring material according to claim 16, which is zirconia-sodium oxide, silica-zirconia-potassium oxide, silica-alumina-sodium oxide, or silica-alumina-potassium oxide. 19. The dental filling / restoring material according to claim 16, wherein the polymerizable monomer is a polymerizable monomer having 2 to 6 meth (acrylic) groups in its molecular structure. 20. A meth (acryl) group having 2 in the molecular structure.
The polymerizable monomer having 6 to 6 is at least one polymerizable monomer selected from the group consisting of bisphenol A diglycidyl (meth) acrylate, triethylene glycol di (meth) acrylate and pentaerythritol tri (meth) acrylate. The dental filling and restorative material according to claim 19, wherein